The present invention relates to the decontamination arts. It finds particular application in connection with an automated system for leak testing cleaning, sterilizing, and drying devices for medical, dental, mortuary, and pharmaceutical applications, and the like, and will be described with particular reference thereto. It should be appreciated, however, that the invention is also applicable to the decontamination of other devices in an automated processing system.
Medical devices, such as endoscopes, and other lumened instruments, are subjected to thorough cleaning and antimicrobial decontamination between each use. During medical procedures, the devices become coated with blood and other protein-rich body fluids. If the instruments are sterilized while they are coated with these materials, the high temperatures and/or chemicals used in the sterilization process tend to cause the materials to set as a hardened layer of biological residue that becomes difficult to remove. Not only do such residues present a barrier to sterilant penetration, but even when sterilized, they may later break down to form toxic substances which pose hazards to patients when the devices are reused.
Traditionally, such devices are often rinsed in a cleaning solution, such as an enzymatic cleaner, to remove the bulk of the blood and other body fluids from their surfaces. The rinsing process is generally carried out manually by immersing the devices in a shallow tray of the cleaning solution. However, for devices such as endoscopes, the cleaning fluid may not penetrate the length of the internal lumen, leaving a portion of the endoscope to become coated with dried body fluids. Additionally, the biological materials and strong cleaners may pose hazards to personnel coming into contact with them.
High temperature sterilization processes, such as steam sterilization in an autoclave, are generally unsuited to the sterilization of endoscopes because of the delicate components and materials from which they are manufactured. The high temperature and pressure tend to curtail the useful life of endoscopes, rubber and plastic devices, lenses, and portions of devices made of polymeric materials and the like. High temperature sterilization alone does not clean. Any body fluids that are not removed prior to thermal sterilization are typically baked on to the instrumentation.
Instruments which cannot withstand the pressure or temperature of the oven autoclave are often microbially decontaminated with gas, such as ethylene oxide gas or hydrogen peroxide vapor. Like steam, gases do not clean, requiring a separate cleaning operation. The ethylene oxide sterilization technique also has several drawbacks. First, the ethylene oxide sterilization cycle tends to be longer than the steam autoclave cycle. Second, some medical equipment can not be sterilized with ethylene oxide gas. Third, ethylene oxide is highly toxic and can present health risks to workers if not handled properly.
Liquid microbial decontamination systems are now utilized for equipment which can not withstand the high temperatures of steam sterilization. Peroxyacetic acid, or peracetic acid, is a useful sterilant and/or disinfectant for a variety of applications, including disinfection of waste and sterilization or disinfection of medical equipment, packaging containers, food processing equipment, and the like. It has a broad spectrum of activity against microorganisms, and is effective even at low temperatures. It poses few disposal problems because it decomposes to compounds which are readily degraded in sewage treatment plants.
In some situations, a technician mixes a disinfectant or sterilant composition with water and then manually immerses the items to be microbially decontaminated in the liquid composition. The high degree of manual labor introduces numerous uncontrolled and unreported variables into the process. There are quality assurance problems with technician errors in the mixing of sterilants, control of immersion times, rinsing of residue, exposure to the ambient atmosphere after the rinsing step, and the like. For sterilizing large, instruments, such as endoscopes with narrow lumens, however, a large receiving tray and a considerable quantity of decontaminant solution are used to accommodate and fully immerse the instruments.
Integrated decontamination systems, such as peracetic acid decontamination systems, have now been developed which provide a premeasured dose of a decontaminant in solution. Items to be sterilized are loaded into a receiving tray of a sterilization system and a cartridge of concentrated decontaminant inserted into a well. As water flows through the system, the decontaminant, which may be accompanied by surfactants and corrosion inhibitors, is diluted and carried to the receiving tray.
The items to be decontaminated are typically loaded into a treatment chamber through an opening closed by a door. It is desirable to maintain a seal between the door and the chamber, to prevent leakage of potentially hazardous sterilization chemicals from the chamber, and also to prevent ingress of potentially contaminated outside air into the chamber once the items are sterile.
Accidental opening of the door during a sterilization cycle poses hazards to operators because of the strong chemicals generally used. Typically, the door includes hinges along one side and a latch mechanism on the opposing side which holds the door securely against the chamber. With large doors, a single latch is often insufficient to maintain a seal along the length of the door. Having multiple latches increases the time required for opening and closing the chamber.
Spraying the exterior of the instruments, while flowing decontaminant solution through the lumens, would have advantages over full immersion of the devices in reducing the quantity of decontaminant solution used. However, because of the complex shape of endoscopes, the spray jets may not reach all of the surfaces of the device. Additionally, interior surfaces of the lumened devices are not reached by the spray.
The present invention provides for a new and improved automated system for reprocessing endoscopes and the like which overcomes the above-referenced problems and others.
In accordance with one aspect of the present invention, a method of cleaning and microbially decontaminating a device is provided. The method includes the sequential steps of positioning the device within a chamber, spraying a washing solution over the device from nozzles within the chamber to remove soil from exterior surfaces of the device, spraying a microbial decontaminant solution over the device from nozzles within the chamber to microbially decontaminate the exterior surfaces of the device, and spraying a sterile rinse fluid over the device from nozzles within the chamber to rinse the exterior surfaces of the device.
In accordance with another aspect of the present invention, a method of cleaning and microbially decontaminating an endoscope is provided. The method includes positioning the endoscope within a chamber, contacting the interior surface and the exterior surface of the endoscope with a washing solution to remove soil from the device, then contacting the interior and the exterior surfaces of the endoscope with a microbial decontaminant solution to microbially decontaminate the endoscope. The method further includes contacting the interior and the exterior surfaces of the endoscope with a sterile rinse fluid to rinse the interior and exterior surfaces of the endoscope and then removing the endoscope from the chamber. The contact steps are automatically controlled.
One advantage of the present invention is that an endoscope or other lumened device is cleaned and microbially decontaminated in a single automated process.
Another advantage of the present invention is that hazards posed to personnel by handling contaminated devices are minimized.
Yet another advantage of the present invention is that a leak resistant closure is created with a single latching mechanism.
A further advantage of the present invention is that the door remains locked during a sterilization cycle.
A yet further advantage of the present invention is that a decontaminant delivery system ensures decontamination of all exterior and interior surfaces of the device being decontaminated.
Another advantage of the present invention is that spraying, rather than fully immersing large items, such as endoscopes, reduces the quantities of water and decontaminant, pretreatment agents, and cleaning agents used.
Still further advantages of the present invention will become apparent to those of ordinary skill in the art upon reading and understanding the following detailed description of the preferred embodiments.